Dr. Rountree emphasized that most studies have been performed on fish oil. "The VAST majority of published research on omega-3 fatty acids has been on EPA + DHA from fish oil, not from krill. I think the push towards krill is mostly a marketing gimmick. I am also concerned about the sustainability of krill. Most of the commercial fish oil supplements come from sardines and anchovies which are much more sustainable."

Todd Runestad had several helpful thoughts.

"You can tell if a fish oil is rancid by the burp or taste. Refrigerating fish oils ought to suffice. Plus, some fish oil suppliers, like Ocean Nutrition Canada, protect the oils in a double-hull, making them suitable for even foods and drinks with no taste or odor issues.

Molecular distillation also makes fish oil supplements largely PCB-free and heavy metal-free. Not the same story with actual fish, because of pollution such as mercury from coal-burning power plants, etc. Cod liver oil was fingered by California’s recent Proposition 65 lawsuit -- stay away from the body's coffee filter [the liver]!

The South America fisheries (where most fish oil comes from, in the form of anchovies and sardines) are largely farmed, and do not have the toxicity issues because prevailing winds to the west coast there are largely clean. Plus heavy metals accumulate as you move up the food chain, which is what makes tuna so risky, but sardines and anchovies are at the bottom. I haven’t heard anything about sustainability issues with the fisheries down there.

I'm a krill fan. The Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) is the international regulatory body that puts an independent assayer on each and every boat in the Antarctic waters. The phospholipid story with krill does indeed give it superior uptake relative to most brands of fish oil. Now, krill does not have nearly the same EPA and DHA content as fish oil—and certainly not as much as some of the high concentrates now available—but if you compare it to the standard 180/120mg EPA/DHA per 1,000mg fish oil capsules, I'd take krill. Some research shows the phospholipds (phosphatidylcholine, to be exact) makes the EPA and DHA about three times better as far as bioavailability goes.

I would heartily second Bob’s comment that the VAST majority of research in this area is with fish oil EPA and DHA (thousands of published studies) and the number of published human clinicals with krill at this time is I think literally three or four."

What do you think about these issues? Do you take fish or krill oil? If so, what brand, and why?